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Storage Creating 2 different RAID arrays, should I use one or two RAID controllers?

Discussion in 'Hardware' started by Bungletron, 18 Apr 2011.

  1. Bungletron

    Bungletron Well-Known Member

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    I am building a server, I intend to have the OS on a RAID 1 array and the storage as a seperate RAID 5 array.

    The motherboard hardware RAID controller supports RAID 1 and I have purchased the High Point PCIE x 4 8x SAS/SATA RAID controller (link) for RAID 5.

    I could actually have the High Point controller managing both arrays or I could use the mobo hardware to manage the RAID 1 array and the controller add-in to manage the RAID 5. I think 2 different controllers managing each array would be fastest but I could not find any info on internets, perhaps someone here could confirm which setup would be faster? In the end if there is no speed difference then I would be more inclined to have the High Point card manage both arrays because the software funcionality, such as drive failure email alerts, seems really useful, either way love to hear what you have got to say!
     
  2. tehBoris

    tehBoris New Member

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    You might see a performance increase, but I doubt it. The OS drive is likely to not be doing much most of the time in any case.
     
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  3. Pookeyhead

    Pookeyhead It's big, and it's clever.

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    I'd use the Highpoint to manage teh RAID5 as it has it's own processor, and RAID5 is quite processing intensive. You don't want PCs processor working on that. RAID1 is far less intensive as it's just mirroring, so I'd run that off the motherboard's controller.
     
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  4. Bungletron

    Bungletron Well-Known Member

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    Interesting, 2 slightly opposing points there, cheers!

    Another thing now, for the RAID 5 array it turns out I have 4x 2TB drives available. Thinking about it I would need no more than 4TB strorage right away. The HighPoint has two interesting features which again give me cause to think about the initial config: Hot Spare and Online Capacity Expansion. I could create a 3 disk RAID 5 array with the forth disk as a Hot Spare (will automatically rebuild array using the hot spare if one of the disks fails) or if I start to reach the 4TB limit add in the the forth disk using Online Capacity Expansion (resizing the RAID 5 array by adding in an extra disk). Alternatively I could just create a 4 disk RAID 5 array from the start.

    I imagine the hot spare will not get caned at all while it is kept as a spare, so if I do not need it's storage capacity right away it would allow me to conserve the drive while having redundancy. My question: Is there a performance boost comparing a 4 disk RAID 5 array to 3 disk? If it is insignificant I probably will not bother making a 4 disk array right away.
     
  5. Pookeyhead

    Pookeyhead It's big, and it's clever.

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    Set the 4th as a hot spare. You can always reconfigure should you need the extra space.

    What you doing about back up though? RAID is not backup.. it's redundancy. It will offer no protection against accidental deletion, corrupt files, or a RAID controller going fubar and hosing your array. System crashes while writing to the RAID can also cause massive problems if you don't have a read/write cache battery back up (which your controller doesn't).

    You need back up.
     
  6. Bungletron

    Bungletron Well-Known Member

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    Yes, a pretty excellent point, I will probably set it up to backup back to a network share on my main rig probably once a week!
     

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